The invention relates to a laser welding device for joining workpieces by means of a laser beam, and to a corresponding method.
Laser beam welding is used in particular in situations in which workpieces have to be joined with high welding travel speed, narrow weld seam shape and low thermal distortion. The workpieces to be joined are fixed in the respective desired position, for example by means of receiving or fixing devices provided for this purpose, and are then connected to one another by means of laser beam welding.
Due to the high light intensities used during laser welding, laser welding devices are general operated in a separate safety cabin, which ensures that the surrounding environment is shielded from the laser radiation. However, such safety cabins increase the spatial requirement of such a device since they generally house the entire laser beam machining device, and the operation of the cabins is complex and costly.
EP 2 149 421 A1 describes a device for welding workpieces by a means of a laser beam, wherein the laser beam of a fibre laser is focused by means of a collimator arranged in a housing. The collimator, which is provided in a pressure portion or pressure piece of the housing, can be moved by means of a linear drive parallel to a discharge slit in such a way that the laser beam can exit from the housing through the discharge slit and can produce a straight weld seam on a workpiece, which is fixed between the pressure piece of the housing and a second pressure piece.
The described linear guidance only enables beam guidance in a straight line, however, and therefore the workpieces to be welded have to be repeatedly repositioned in order to produce curved weld seams, said process therefore requiring an accordingly high expenditure of time. Furthermore, the feed rate of the laser process is predefined by the linear drive and for example is limited due to the mechanical stability of the collimator system, wherein such collimators generally comprise sensitive optical components and therefore for example should not be exposed to excessively high accelerations.
Furthermore, EP 2 149 421 A1 does not specify the shape or design of the workpieces to be machined; for example the described device and the respective pressure pieces do not take into account the fact that the shape of the workpieces to be fixed may vary and/or that workpieces with an irregular (for example non-co-planar, but for example three-dimensionally curved or stepped) shape may have to be machined. When machining workpieces with such an irregular design, it may be for example that the discharge slit of the housing cannot be completely covered by the workpiece, and therefore laser radiation may exit past the workpiece from the housing and for example may come into contact with individuals.